1.
When you say "football" here, in America, what people around you think of, as long as they're fellow Americans, is either the NFL or the college version of American football. If you're in Calgary or Winnipeg and mention "football", people there understand you to mean a game we call Canadian football. If you mention "footy" in Australia, they assume you're talking about what we call Australian rules football. In London, "footy" or "football" means a game we usually call soccer.
In Dublin, the highest attended sporting event is football, but not soccer, rather, a game known outside of Ireland as Gaelic football.
An interesting thing about the term "football": in as many places as have unique games using a ball and feet in some capacity all colloquially refer to their game as simply football.
America, Canada, Australia, Ireland, and England all have games that the locals call football, and all are different from each other. Is anyone more right than anyone else?
2.
Skipping the thousands of years of history of indigenous peoples use of games as battle practice would do a disservice to this discussion. But, a thorough discussion of those peoples and their games would take too much time.
Believe me, almost all groups of native peoples throughout human history had games of some kind, many used primarily to keep young warriors fit and teach them coordination and teamwork, things that would help out in the eventual battles they'd end up in. Many of these games used a sphere of dense vegetation or and inflated animal bladder as the "ball".
It was this background of mobbed-sporting-event that we'll move this discussion to Europe, and, specifically, England.
3.
In Medieval England tiny villages would have game contests during major holidays. They started halfway between the towns with an unlimited number of participants ("players"), and the winner was the town that could move the inflated bladder-ball to the opposing town's abbey or church.
This "mob-ball" game was the basis for all our games today that bear the name football. In those contests, people were allowed to pitch the ball, kick it, advance it in someway that wasn't directly carrying it and running. People had loads of fun, and not too many were gravely injured.
4.
In the mid 1500s, students of the affluent and aristocratic classes went to schools instead of to work, like their poorer counterparts, in places we today "English public schools" that were in fact what we'd understand as being private schools.
As early as then, these institutions were trying to find ways to keep the kids fit and in shape, and teach them teamwork and cooperation. It was over the next two centuries that it's understood that these schools turned "mob-ball" from a day long playful battle into an organized sporting event.
The thing was, each school developed their own game (a few of which still exist). Almost all of these schools called their game football.
An interesting thing about the development of these games is their development through their limitations. For schools that had large amounts of open space, a carrying type of football game developed, where an oblong ball could be carried by hand and passed by foot, and tumbling and tackling could take place. One school that had this kind of game develop was named Rugby.
Other schools that had less space to develop their games tended towards a kicking type of game, with less emphasis on tumbling, tackling, and holding the ball with your hands.
When rail travel made traveling easier, schools would travel and play opposing schools, playing one half of the game using one school's football rules, and the second half using the other's.
5.
In America, two specific years revolutionized the game we call football, and they involved rule changes. The first was 1880. That was the year that the Yale coach was able to implement rule changes to the version of Canadian rugby they played and convinced the schools they played against to switch as well. Not everybody switched right away, but they all ended up on the same page eventually.
Those rule changes? The establishment of a line of scrimmage and a set of downs to advance the ball a set distance before turning it over changed the strategy immensely. Now that the action stopped between advancing the ball, the game started to resemble its continuous-play rugby basis less and less. This development also started the evolution of scripted plays, something up until then was unknown.
In the football that's world known and beloved, known as Association Football, or soccer, scripted plays are reduced to set-plays like the corner kick, or the long free-kick.
The other year that made American football resemble what we see today was 1905, when the game was almost outlawed and the rules were changed to reduce violence. They made legal the play we call a "forward pass", they changed first down from 5 yards to 10, and lastly they changed the number of downs to make the yardage from 3 to 4.
A forward pass is still an illegal play in both kinds of rugby, our football's most obvious ancestor.
If you think football is violent now (it is, very much so), you should have seen it in 1905. There were some years when more than 50 players died on the field, and nearly 200 were seriously injured, like life-altering injuries. It's no surprise that they were talking about outlawing it. They were talking about making it safer then, as they are now. Nowadays, of course, the problem is brain injuries and long-term concussion issues.
6.
Canadian football is one of the three North American styles of "gridiron football". They use a different size ball than the NFL (and NCAA), they use a 110 yard field (instead of 100 for NFL), they retain the 3-down setup instead of the NFL's 4-down, and there's no limit to pre-snap motions on their backs on offense. That's a lot of words talking about the differences, but Canadian football is very similar to NFL and NCAA.
College football in America is different from the NFL, but not terribly.
Gaelic football, the most popular football game in Ireland, is an amateur sport that resembles soccer and basketball, with players running down a field dribbling the ball like a basketball with their feet. It's hard tio explain, but fun to watch and easy to grasp what's going on.
Aussie rules football is played on a large oval, and the point is to kick the ball through uprights, or run it in; both plays have different point totals. It's exciting to watch, but takes a few minutes to tell why people hand over the ball after certain plays, and why certain players can't run, or can run...it's cool, though.
Rugby is split into two versions, and they resemble each other even if they're further apart than the NFL and NCAA. Rugby is the great-granddaddy of all grid-iron style football games, as well as those variations that use oblong balls and hands as well as feet (Aussie rules and Gaelic, et al). It is exciting, and as an American, I can see how the development of our football evolved through simple rule changes.
Association football is the world's most popular team sport. Soccer, baby!
7.
Happy Turkey Day! Thanksgiving is my favorite American holiday in the Oct-Nov-Dec-New Years holiday season. As a harvest celebration, the basis is that the earth is giving gifts to you.
And a tradition here is to have our football on in the background--or foreground--during the Thursday itself.
Not for everybody, of course, but I hope all have a nice few days, celebrating the great American pagan harvest festival.